Mutual communication between two communication terminals, such as portable telephones, personal computers or the like, is usually carried out through a predetermined communication network in the form of wireless system or wire system. There has been proposed a wireless communication network by the name of mesh network as one of such communication networks.
The mesh network is different from a known communication network constituted with a base node which functions as a central controller and a plurality of relay nodes which are under the control by the base node. In the mesh network, any node corresponding to the base node functioning as the central controller is not provided but a plurality of relay nodes are provided in such a manner that each contiguous two of the relay nodes are placed with their communication areas overlapping partially with each other so that communication paths extend reticulately. With the mesh network, the following advantages can be obtained. For example, when a certain one of the relay nodes provided in the mesh network is put in a condition for interrupting communication, the communication is rapidly revived through another relay node provided in the mesh network. In addition, it is easy to add a new relay node to the network.
With regard to the mesh network as mentioned above, various technical improvements have been proposed. For example, with one of such technical improvements, a communication signal which is received and transmitted by each of the relay nodes provided in the mesh network is changed in its signal characteristics, such as a rate of signal, a manner of modulation, a frequency band and so on, in response to the signal receiving capacity of the relay node so that the amount of information processed in a predetermined time in the mesh network is increased (as disclosed in, for example, patent document 1). Further, with another technical improvement, each of the relay nodes constituting the mesh network is provided with a directive antenna system and the directivity of antenna determined by the directive antenna system is selected in response to the communication carried out through the subject relay node so that the communication efficiency in the mesh network is improved (as disclosed in, for example, patent document 2).
The patent document 1: U.S. Pat. No. 6,480,497
The patent document 2: U.S. Pat. No. 6,640,087